Fast-charging, battery charging systems are distinguished from other battery charging systems in that they operate to produce a battery charging output with a higher kilowatt output and approximately twice, or greater, the charging rate than traditional battery charging systems. An industrial-type, fast charging, battery charging system can include a power supply connected to one or more charging stations, and the charging stations can have output currents up to 500 A or greater, and power outputs up to 30 kW and greater. Compatible battery voltages are typically 12 to 80 volts from a lead-acid battery or battery bank. The industrial-type, fast charging, battery chargers can typically be used for charging lift trucks, fork lifts, golf carts, and the like, which chargers operate at relatively higher electrical power levels to charge a 12-80 volts direct current (VDC) battery system. In these systems, the battery is the main power source for driving the fork lift, golf cart, and the like.
These fast charging systems can have a primary side switched-mode power supply that converts a mains alternating current (AC) electrical power into a suitable direct current (DC) electrical power. In general terms, the fast-charging, battery charger, power supply can include input terminals for mains input, and an input rectifier and filter for filtering and rectifying the mains input, an inverter for converting the rectified input power to a higher frequency, a high frequency transformer which converts the voltage up or down to the required output level on its secondary winding(s), and another rectifier and/or filter (output circuit) to provide a suitable DC battery charging power. Mains power can be 120, 240, 480, 600, or higher, VAC, and single phase or multiphase being typical for the higher voltages. A switched-mode power supply has the advantage of providing a relatively high frequency to the transformer, which allows the transformer to be smaller for a given current capacity, as transformer size is inversely related to operating frequency.
Fast-charging, battery charger, power supplies can generally require a number of heat generating electrical devices such as transformers, power modules which may have insulated gate bipolar transistor (IGBT) switching modules, inductors, rectifiers, transducers and the like interconnected through circuit boards, connectors, cables, etc. Because of the high current and/or voltages involved, such power supplies can have electrical devices as mentioned which generate a considerable amount of heat which needs to be dissipated in order to prevent damage to the battery charging power supply, and to increase the reliability of the battery charging power supply. Some of these devices (e.g., transformers) are relatively robust, whereas other (e.g., the integrated circuits used on the power modules and other circuit boards) are susceptible to contaminants and other elements such as static electricity.
For safety and other reasons, fast-charging power supplies include a housing which is generally enclosed, and which restricts natural convection cooling of the electronic components required to transform input energy into a battery charging output. Louvers may be constructed into the housing to accommodate air flow through the housing, and also fans have often been incorporated into the assembly of some the battery charging power supplies to facilitate improved cooling of the electrical components. Such air flow can create the additional problem of introducing heavy particulate flow into the interior of the housing. These particulates can build up on various components, and more particularly the printed circuit boards, and can effectively shorten the useful life or reliability of certain electrical components of the power supply.
Some cooling methods allowed for a cooling flow to follow a labyrinth path through the entire battery charging power supply housing. Although this may improve the cooling of some of the electrical components, it did not address the problem of particulate accumulation on certain electrical components because there was no separation between the cooling flow and the sensitive electrical components. Other methods have increased the complexity of the assembly of the power supply and hinder assembly by preventing assembly of the electrical components of the power supply prior to installation of the electrical assembly within the power supply housing.
What is needed in the art is a system and method capable of separating the electrical components into those that are preferred to be located in a cooling flow from those that are preferred to be located outside a cooling flow while also providing simplified and cost effective assembly processes.